Early Jurassic Ataphridae (Gastropoda) of Chubut, Argentina: paleogeographic and paleoecologic implications

Abstract

The Ataphridae were recently characterized by a number of diagnostic features related to the general morphology of the peristome, the aperture and the columelar lip. This family is common and widely ditributed in the Mesozoic of Europe, where the Ataphrini is the most abundant and diverse group within the Jurassic Ataphridae. In South America, however, the ocurrence of Striatoconulus in the Early Jurassic of Chubut province was the only mention of the family so far. Following the new systematic classification of the Ataphridae, two new species are described here: Ataphrus mulanguiniensis sp. nov. and Chartronella paganiae sp. nov. Other two doubtfully referred members of the family are mentioned: Chartronella? sp. and Lewisiella? sp. The new findings here reported from the Early Jurassic of Chubut province contribute to the biodiversity knowledge of the group in Argentina, extending its paleogeographic distribution in the Jurassic of South America. An abundant and diverse invertebrate fauna found in association with the ataphrid-genera indicates a litoral marine environment for the gastropod-bearing sediments.